Acoustic cabinet



United States Patent ACOUSTIC CABINET Wilhehnus Adrianus Jacobus Liebert, Hilversum, Netherlands Application August 2, 1952, Serial No. 302,308

Claims priority, application Netherlands August 7, 1951 1 Claim. (Cl. 181-31) The invention relates to a cabinet for an apparatus which is provided with a loudspeaker, as for instance a radio apparatus, a gramophone or a television receiver. In such an apparatus the loudspeaker has generally been mounted in the front wall of a closed cabinet. In consequence the acoustic power radiated by the loudspeaker at its back side is absorbed in the cabinet and is lost for a considerable part.

An object of the invention is to provide a cabinet in which the loudspeaker is mounted in such a way that the acoustic power radiated at the front side of the loudspeaker as well as that radiated at the back side thereof is fully utilized. According to the invention to obtain this result the loudspeaker is mounted in the middle one of three intersecting planes in such a way that the acoustic vibrations radiated by the loudspeaker at its front and at its back side are reflected sidewardly by both the exterior planes.

Another object of the invention is to provide a cabinet for an apparatus provided with a loudspeaker wherein the said three planes are formed by three separate soundboards, the middle one of which is preferably placed in a horizontal position, whilst at least one of the outermost soundboards is adapted to be adjusted at different angles with respect to the middle one, so that the angle of one of the reflecting boards may be chosen in such a way, also with respect to the sound reflection of other surfaces as for instance walls, floor and ceiling of the room, that at the place of observation no unfavourable influences is endured from the difference of phases existing between the sound vibrations radiated and reflected at the front side and those radiated and reflected at the back side of the loudspeaker. It is not necessary that all Soundboards are flat. One soundboard or both of the exterior boards may as well be provided with a concave or a convex curved surface according to the desirability to obtain a greater or smaller dispersion of the reflected sound vibrations.

Still another object of the invention is to provide a cabinet for an apparatus provided with a loudspeaker, which is placed on legs or columns and is provided with a soundboard directed slantingly upwards and backwards and mounted between the said legs or columns, and wherein the loudspeaker is mounted in a horizontal position free at its top and bottom, the upper side of the cabinet being covered by a hinged cover, which forms the other reflecting soundboard.

The invention will now be described with reference to the accompanying drawings.

Fig. 1 shows the principle on which the invention is based.

Fig. 2 shows a top view of an embodiment of a cabinet according to the invention, the said cover being omitted in this figure.

Fig. 3 shows a section according to the line IIIIII in Fig. 2.

Fig. 4 shows a front view of the embodiment of the invention according to the Figures 2 and 3.

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As shown in Fig. l the loudspeaker 1 has been mounted in the middle one 2 of three converging Soundboards, the outermost soundboards being adapted to reflect the acoustic vibrations radiated by the loudspeaker 1 at its front and back sides. The boards 3 and 4 may be flat. Moreover they may be adapted to be adjusted at different angles with the board 2. In another embodiment of the invention one of the outermost boards or both of them may have a curved form or these boards may form a complete paraboloid, the loudspeaker being placed in the focal point thereof. The board 2 may also be placed in a position deviating from the horizontal plane, for instance in a vertical position in the corner of a room, so that the soundboards 3 and 4 coincide with two vertical walls of the room. If it is desirable to radiate the sound in different directions, the boards 3 and 4 may be placed in a distorted position with respect to each other and may be opened in different directions.

Figures 2-4 show a cabinet for a radio-gramophoneset according to the invention. The cabinet 5 is provided with a hinged cover 6, which may be fastened by means of supporting rods 7 of adjustable length in different positions thus forming one of the reflecting Soundboards. The cabinet 5 is supported by four legs 8 and the second slantingly mounted soundboard 9 is fixedly mounted between these legs. This soundboard may be flat as shown in the figure. However, it is likewise possible to execute this board in a curved form.

In the front part of the cabinet, a space 10 has been separated by walls 14, 15 in which space the radio and gramophone apparatus has been placed, the tuning-dial 11 with dialling-knobs 12 and the turntable 13 being mounted on the horizontal wall 14. The backpart of the cabinet comprises two side compartments 16, separated by walls 18 and open on their upper sides, which compartments are destined for storing the records.

The walls 15, 18 and the back wall 19 of the cabinet enclose the space wherein the loudspeaker 20 is placed. This space opens at its upper side under the cover 6 whilst on its lower side it is accessible through an aperture 21 in the bottom wall of the cabinet 5. In the middle of this space the horizontal soundboard 22 of the loudspeaker 20 is arranged. Thus the sound vibrations radiated by the loudspeaker are leaving the said space on its lower side through the said aperture 21 and are thrown into the room after being reflected by the soundboard 9 whilst the sound vibrations radiated by the loudspeaker at its upper side are reflected by the open cover 6 in the same direction. By adjusting the angle of opening of the cover the most favourable effect can be aimed at.

Many variations of the described embodiment of the invention may be performed without leaving the scope of the invention. Thus, it is possible, for instance, to arrange two or more loudspeakers in the described position in one cabinet. In a television set the picture screen may be inserted in the front wall of the cabinet or in an elevated part under the cover.

The acoustic cabinet according to the invention makes it possible to obtain a more favourable useful effect and to provide at the same time a piece of furniture of a greater elegance than most of the known radiocabinets.

What I claim is:

A cabinet for a radio, phonograph, television receiver and like instrument having a loudspeaker, comprising, in combination, a cabinet body, means defining a separate box-shaped chamber in the rear of said cabinet provided with a lower opening and an upper opening, a horizontal speaker supporting soundboard positioned in said chamber, a speaker mounted in said soundboard and positioned to emit sound waves upwardly and downwardly from both faces of said plate through said lower opening and said upper opening, a cover hinged to said cabinet positioned to receive the upwardly directed sound Waves from said speaker and to reflect them forwardly from said cabinet in a horizontal direction, spaced apart columns supporting said cabinet, a reflecting screen mounted between said columns in a slanting position to receive the downwardly directed sound waves from said speaker and to reflect them forwardly in a horizontal direction, said cover and said screen being substantially equally spaced from said supporting soundboard, whereby said soundboard bisects the angle defined between said cover and said soundboard to provide an acoustic dipole.

References Cited in the file of this patent UNITED STATES PATENTS 

